Mobile products (e.g., mobile phones, smart phones, tablet computers, etc.) are typically very restricted in available space because there are often severe limitations for chip and package area and height (among other physical and electrical parameters). Therefore, it is extremely important to reduce the size of electronic components (e.g., dies) on a substrate.
However, when electronic components/packages are made relatively thin in order to accommodate this need for reduced sized electronic components, there can be difficulties that are associated with fabricating such components. As an example, thin components/packages have historically been a huge challenge for the semiconductor industry.
Some electronic components/packages include a silicon die that has a relatively low coefficient of thermal expansion (CTE) attached to a substrate that has a high CTE. Therefore, manufacturing difficulties often arise because the die is attached to the substrate which warps with temperature changes during fabrication of the components/packages. The differences in the CTE between the die and the substrate can make it extremely difficult to balance the design and material properties in a components/package in order to obtain a flat package at (i) room temperature; and (ii) bump melting temperature.
One approach to addressing manufacturing difficulties that are caused by the differences in the CTE between the die and the substrate is to include a mold material in the component/package in order to provide rigidity. Adding a mold material to the component/package suffers from several drawbacks. First, an added mold may often have non-linear material properties that result in increased stress within the component/package. Second, an added mold usually increases the overall size of the component/package (especially the Z height of the component/package). Finally, high performance components/packages usually need to remove sections of the mold in order to expose parts of the component/package from the mold. Removing parts of the mold may reduce the effectiveness of the mold relative to warpage reduction.
Another approach to addressing manufacturing difficulties that are caused by the differences in the CTE between the die and the substrate is to use metal or some other material as a stiffener. Adding a stiffener to the component/package suffers from several drawbacks. First, an added stiffener may increase the overall size of the component/package (especially the Z height of the component/package). In addition, adding a stiffener to a component/package may also limit the thermal dissipation of the component/package due to adhesive material between stiffener and silicon on the component/package.
Still another approach to addressing manufacturing difficulties that are caused by the differences in the CTE between the die and the substrate is to design the components/packages with thicker core substrates. However, making the components/packages with thicker core substrates would inherently undesirably increase the overall z-height of the components/packages with thicker core substrates.
Still another approach to addressing manufacturing difficulties that are caused by the differences in the CTE between the die and the substrate is to design the components/packages with thinner dies. However, even though thinner die architectures may provide reduced warpage to a component/package, thinner die architectures often have significantly worse transistor performance within the die.